The present invention relates to a top-fired, lifting or walking, hearth-type furnace for the heating of billets, ingots or similar stock by means of hot flue gases circulating through the furnace.
Even during the initial phase of heating by means of this type of furnace, the heating of such stock must occur as evenly as possible in order to prevent stock from cracking or bending, such occurrences being caused by internal stresses as a result of uneven heating. If the temperature of the stock increases too rapidly, the stock may warp on the upper or lower side due to varying temperature effects. Therefore, in the past this type of furnace has been operated at low temperatures in a preheating zone or has been equipped with expensive mechanisms for turning over the stock to ensure uniform heating thereof.